Tropical Weather Discussion
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000
AXNT20 KNHC 290551
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SAT AUG 29 2015

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF
SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE
EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE
IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL
ANALYSIS.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0545 UTC.

...SPECIAL FEATURES...

TROPICAL STORM ERIKA IS CENTERED NEAR 18.5N 72.9W AT 29/0300 UTC
OR ABOUT 35 NM W OF PORT AU PRINCE HAITI AND ABOUT 126 NM SE OF
THE EASTERN TIP OF CUBA MOVING W AT 17 KT. ESTIMATED CENTRAL
PRESSURE IS 1008 MB. MAXIMUM SUSTAINED WIND SPEED IS 40 KT WITH
GUSTS TO 50 KT. A CLUSTER OF MODERATE TO ISOLATED STRONG
CONVECTION EXTENDS FROM 15N-21N BETWEEN 68W-74W. THE MAIN IMPACT
OUTSIDE OF TROPICAL STORM FORCE WINDS WILL BE HEAVY RAINFALL
ACROSS HISPANIOLA AND THE ADJACENT COASTAL WATERS RESULTING IN
FLASH FLOODING AND DANGEROUS MUD SLIDES. SEE LATEST NHC
INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS
MIATCPAT5/WTNT35 KNHC AND THE FULL FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT5/WTNT25 KNHC FOR MORE DETAILS.

...TROPICAL WAVES...

A TROPICAL WAVE IS BEGINNING TO EXIT THE AFRICAN COAST. ITS AXIS
EXTENDS FROM 19N15W TO 07N14W. LATEST VISIBLE SATELLITE IMAGERY
SHOWS A HINT OF LOW-LEVEL CYCLONIC CIRCULATION TRYING TO DEVELOP
ALONG THIS WAVE. SCATTERED MODERATE TO STRONG CONVECTION IS IN
THE SOUTHERN PORTION OF THIS WAVE FROM 07N-11N BETWEEN 12W-18W.

A TROPICAL WAVE IS OVER THE CENTRAL ATLANTIC ASSOCIATED WITH A
1014 MB LOW EMBEDDED IN THE MONSOON TROUGH NEAR 13N41W. THE WAVE
AXIS EXTENDS FROM 17N39W TO 08N42W. THESE FEATURES ARE MOVING W
AT ABOUT 15-20 KT OVER THE LAST 24 HOURS. MODERATE MOISTURE IS
ASSOCIATED WITH THIS WAVE FROM THE SURFACE TO 700 MB AS
INDICATED BY CIRA LAYER PRECIPITABLE WATER IMAGERY. UPPER LEVEL
DIFFLUENCE W OF THE LOW SUPPORTS ISOLATED MODERATE CONVECTION
FROM 12N-17N BETWEEN 44W-47W WHILE ISOLATED MODERATE CONVECTION
PREVAILS ACROSS THE WAVE AXIS FROM 13N-15N BETWEEN 39W-41W.

A TROPICAL WAVE IS WITHIN 285 NM E OF THE LESSER ANTILLES WITH
AXIS EXTENDING FROM 20N51W TO 09N57W...MOVING W AT 15 KT DURING
THE PAST 24 HOURS. MODERATE MOISTURE FROM THE SURFACE TO NEARLY
700 MB IS ASSOCIATED WITH THIS WAVE AS INDICATED BY CIRA LAYER
PRECIPITABLE WATER IMAGERY. ISOLATED MODERATE CONVECTION
PREVAILS ACROSS THE WESTERN PORTION OF THE WAVE EXTENDING FROM
10N-18N BETWEEN 54W-59W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH AXIS EXTENDS FROM THE AFRICAN COAST NEAR
10N14W TO 11N43W. THE INTERTROPICAL CONVERGENCE ZONE AXIS
EXTENDS FROM THAT POINT TO 08N54W. ASIDE FROM CONVECTION
ASSOCIATED WITH THE TROPICAL WAVES...SCATTERED MODERATE
CONVECTION PREVAILS WITHIN 100 NM S OF THE MONSOON TROUGH AXIS.

...DISCUSSION...

GULF OF MEXICO...

A BROAD AND ELONGATED MID TO UPPER-LEVEL LOW IS CENTERED OVER
THE NORTH-CENTRAL GULF NEAR 29N89W WITH ITS TROUGH EXTENDING SW
INTO THE BAY OF CAMPECHE. THE TROUGHING SUPPORTS A DISSIPATING
STATIONARY FRONT THAT MEANDERS FROM THE FLORIDA PANHANDLE NEAR
31N86W SW TO 26N86W TO 23N96W. UPPER-LEVEL DIFFLUENCE IS
SUPPORTING ISOLATED MODERATE CONVECTION E OF THE NORTHERN
PORTION OF THE FRONT AFFECTING THE E GULF E OF 88W.
SCATTEROMETER DATA DEPICTS A LIGHT TO GENTLE EASTERLY FLOW
PREVAILING ACROSS THE BASIN. OVER THE NEXT 24 HOURS...EXPECT FOR
THE FRONT TO DISSIPATE. TROPICAL STORM ERIKA IS EXPECTED TO
APPROACH THE SE GULF AFFECTING THE FLORIDA PENINSULA...STRAITS
AND KEYS. FOR MORE DETAILS ABOUT ERIKA...PLEASE REFER TO THE
SECTION ABOVE.

CARIBBEAN SEA...

TROPICAL STORM ERIKA IS THE MAIN FEATURE OF INTEREST IN THE
CARIBBEAN...CURRENTLY MOVING ACROSS SOUTHERN HISPANIOLA. PLEASE
REFER TO THE SECTION ABOVE FOR DETAILS. ISOLATED CONVECTION IS
OBSERVED ACROSS THE NW CARIBBEAN SUPPORTED BY UPPER-LEVEL
DIFFLUENCE MAINLY N OF 20N AND W OF 79W. THE REMAINDER OF THE
BASIN REMAIN RELATIVELY QUIET WITH MOSTLY DRY AIR NOTED ON WATER
VAPOR IMAGERY ALOFT DUE TO AN UPPER-LEVEL RIDGE ANCHORED NEAR
17N83W COVERING THE W AND CENTRAL BASIN. ISOLATED SHOWERS ARE
ACROSS PUERTO RICO AND COASTAL WATERS DUE TO THE PROXIMITY OF
ERIKA. SCATTEROMETER DATA DEPICTS MODERATE TO OCCASIONAL FRESH E-
NE TRADES ACROSS PORTIONS OF THE W AND CENTRAL   CARIBBEAN DUE
TO ERIKA WHILE GENTLE TO MODERATE TRADES PREVAIL OVER THE
REMAINDER OF THE BASIN. OVER THE NEXT 24 HOURS...EXPECT FOR
ERIKA TO MOVE NW INTO THE ATLANTIC WITH CONVECTION.

...HISPANIOLA...

THE CENTER OF TROPICAL STORM ERIKA IS EXPECTED TO MOVING OVER
HAITI AT THIS TIME. THE MAIN IMPACT FROM ERIKA ASIDE FROM
TROPICAL STORM FORCE WINDS IS HEAVY RAINFALL WITH THE POTENTIAL
OF LIFE-THREATENING FLASH FLOODS AND MUD SLIDES. THE CENTER OF
THE STORM IS FORECAST TO MOVE TO THE WINDWARD PASSAGE SATURDAY
MORNING BUT SHOWERS ARE EXPECTED TO CONTINUE THROUGH SUNDAY
MORNING.

ATLANTIC OCEAN...

A MID TO UPPER-LEVEL DIFFLUENCE ACROSS THE SW ATLANTIC IS
SUPPORTING SCATTERED SHOWERS AND ISOLATED TSTMS N OF 27N W OF
72W...AFFECTING THE N BAHAMAS. SCATTERED HEAVY SHOWERS ARE OVER
HISPANIOLA NORTHERN WATERS ASSOCIATED WITH TROPICAL STORM ERIKA
THAT IS EXPECTED TO CONTINUE MOVE ACROSS THE ISLAND TONIGHT. THE
REMAINDER OF THE BASIN IS DOMINATED BY A SURFACE RIDGE ANCHORED
BY A PAIR OF SURFACE HIGHS...A 1021 MB LOCATED NEAR 29N65W AND
THE OTHER A 1020 MB CENTERED NEAR 26N32W.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$

ERA


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